In general, in order to inspect the electrical properties of a device, the device has to be stably electrically connected to a test apparatus. In general, a test socket is used as a tool for electrically connecting the device and the test apparatus.
The test socket is used to connect terminals of the device and pads of the test is apparatus and enable electrical signals to be exchanged between the device and the test apparatus. For this purpose, the test socket includes an elastic conductive sheet or a pogo pin as a connection medium. The elastic conductive sheet that connects elastic conductive parts to the terminals of the device to be inspected and the pogo pin that includes a spring therein are used in most test sockets to easily establish a connection between a device to be inspected and a test apparatus, and may also reduce a mechanical impact during the connection.
A test socket including an elastic conductive sheet according to the conventional technology is disclosed in Korean Patent Publication No. 10-2005-0087400 as shown in FIGS. 1 and 2. A test socket 10 includes a socket housing 2 that has a frame shape and has an opening 2a that is formed in a central portion thereof and through which a semiconductor package 1 may be input/output, and a gate plate 5 that has an insulating plate shape, is closely fixed to a top surface of a test board 3 via the socket housing 2, and allows a plurality of contactors 4 that are provided thereon to be electrically connected between terminals of the semiconductor package 1 and a contact pad 3a of the test board 3. The contactors 4 include conductive rubbers 6 that adhesively fill upper portions of inner areas of through-holes that vertically pass through the guide plate and contact pins 7 that are inserted into lower portions of the inner areas of the through-holes, are attached to the conductive rubbers 6, and protrude downward by different lengths.
According to the test socket of FIGS. 1 and 2, in order to align the contactors on the test board, a separate socket housing that is coupled by bolts to the test board has to be provided. When the socket housing is used, sufficient use of a space around the test board is limited. That is, a space of the test board on which the socket housing is seated is not used, thereby reducing the overall space use efficiency.
Also, as shown in FIG. 3, other test socket including a pogo pin according to the conventional technology is disclosed in Korean Patent Publication No. 10-2009-0094584. The test socket includes a housing 10 that includes a receiving part 11 in which a semiconductor chip is received and upper connector holes 12 that are formed in a lower portion of the receiving part 11; a base cover 20 that is coupled to a lower portion of the housing 10 and has lower connector holes 21 formed therein; a connector 30 that is coupled to the upper and lower connector holes 12 and 21 and has a lower portion that contacts a substrate and an upper portion that contacts the semiconductor chip; and a ground block 40 that is coupled between the housing 10 and the base cover 20, has a plate shape, has ground connector holes 41 formed therein, and electrically grounds ground connectors 32 of the connector 30.
The test socket according to the conventional technology has also a problem in that use of a space of the test board is limited due to the base cover that is seated on the test board. That is, a space occupied by the base cover is not sufficiently used, thereby reducing the overall space use efficiency.
A test socket as shown in FIGS. 4 and 5 has been suggested in order to maximize space utilization of a test board of FIGS. 1 through 3.
The test socket of FIGS. 4 and 5 includes an interface substrate 10 that is coupled by soldering to a test board 40, an elastic conductive sheet 20 that is disposed on the substrate, and a guide block 30 that fixes the elastic conductive sheet 20 to the interface substrate. In detail, when predetermined components 42 are arranged around an inspection area where a plurality of inspection pads are arranged, the interface substrate 10 including terminals that are adhered by soldering to the inspection pads 41 is fixed. Via holes 12 that may vertically communicate are formed in a central portion 10′ of the interface substrate 10, upper terminals 11 that contact elastic portions of the elastic conductive sheet are disposed on upper ends of the via holes, and solder balls 13 that are adhered by soldering to the inspection pads are disposed on lower ends of the via holes. The interface substrate 10 may be fixed to the test board 40 when the solder balls 13 are respectively adhered to the inspection pads 41 by soldering. A lower end of a peripheral portion 10″ that is formed around a central portion of the interface substrate is processed to have a stepped portion, and thus components that are arranged around the inspection area are prevented from interfering with each other due to a space that is formed by the stepped portion. Through-holes 14 that may align the guide block are formed in the peripheral portion 10″, and thus the elastic conductive sheet 20 that is disposed between the peripheral portion 10″ and the guide block 30 may be aligned when guide pins 31 of the guide block 30 are inserted into the through-holes. A device to be inspected 50 is configured to contact a top surface of the elastic conductive sheet 20.
The test socket according to the conventional technology has an advantage in that the peripheral portion of the inspection area of the test board may be more sufficiently used in terms of space utilization than the test socket of FIGS. 1 through 3. That is, even when predetermined components are arranged around the inspection area, since the lower end of the peripheral portion of the interface substrate is processed to have the stepped portion, the components are prevented from interfering with each other due to a space that is formed by the stepped portion.
The test socket of FIGS. 4 and 5 has the following problems.
First, an electrical signal is transmitted from the test board to a semiconductor package through the interface substrate and the elastic conductive sheet. Accordingly, an overall current pass is longer than that of the test socket of FIGS. 1 through 3, and thus, the electrical signal transmission characteristics are degraded.
Also, high temperature heat is applied to the test board when the interface substrate and the test board are adhered to each other by using soldering. In this case, the test board may be damaged. Since the test board is more expensive than the test socket, when the test board is damaged, costs for replacing the test board are excessively high.
Also, as the interface substrate is additionally provided, an overall size of the apparatus is increased. That is, as the interface substrate is provided, a size of the test socket is increased.